Boat assemblies



Feb. 5,. 1963 Filed Jan. 20, 1960 FIGJ L. J. NOWAK, JR

BOAT ASSEMBLIES 4 Sheets-Sheet 1 INVENTOR. LEON J. NOWAK JR.

ATTO RNEYS Feb. 5,1963

Filed Jan. 20, 1960 J. NOWAK, JR 3,076,204

BOAT ASSEMBLIES 4 Sheets-Sheet 2 INVENTOR. LEON J.NOWAK JR.

m BY KT. m

ATTORNEYS.

Feb. 5,- 1963 J. NOWAK, JR

.BOAT ASSEMBLIES 4 Sheets-Sheet 3 v Filed Jan. 20, 1960 INVENTOR.LEONJ-NOWA K JR.

ATTO RNEYS L- J. NOWAK, JR

BOAT ASSEMBLIES Feb. 5,1963

4 SheetsSheet 4 Filed Jan. 20, 1960 INVENTOR. LEON J NOWAK JR.

ATTORNEYS United States Patent 3,076,204 BOAT ASSEMBLIES Leon J. Nowak,Jr., 624 S. Knight, Park Ridge, 111. Filed Jan. 20, 1960, Ser. No. 3,66013 Claims. (Cl. 9-6) This invention is directed to boat assemblies andparticularly directed to power boats.

Most present day power boats, which may b charact-erized as outboard orinboard, have relatively rigid hulls made up of wood and in some casesmetal or plastic material. These hulls are oftentimes constructed withelaborate keel and rib frame reinforcing to provide strength for thehull. These hull constructions, while entirely adequate for smoothwaters, ar limited in rough waters. The pounding action of the Wavesimposes severe stresses on the hull and in rough waters most pres entday boat constructions must proceed at extremely low speeds to avoiddamage to the hull. Furthermore, these relatively rigid hullconstructions are oftentimes broken when encountering driftwood or otherforeign objects in the water. Another disadvantage of present day boatsis the vibration which is readily transmitted through the rigid hullsthereof.

A primary purpose of the present invention is to provide a new boat hulland a new arrangement of a prime mover therefor so as to overcome someof the deficiencies of prior boat constructions.

Another object of the invention is to so construct a hull constructionand engine unit therefor so as to improve the safety of the boat.

Another purpose is to so construct a boat hull as to enable variances inriding or planing qualities, while at the same time improving theability of the hull to stand shock from waves or floating debris,minimizing bottom fouling, and minimizing the cost of construction.

Another purpose of the present invention is to construct a boat hull andan engine unit therefor which minimizes vibration of the boat assembly.

Another purpose of the present invention is to so arrange an engine unitfor a power boat as to enable assembly thereof from standard and readilyaccessible parts, and at the same time so arrange the engine unit foreasy replacement of parts or the entire engine unit.

Other purposes will appear from time to time in the course of theensuing specification and claims, when taken with the accompanyingdrawings in which:

FIGURE 1 is a side view of the assembled hull and engine unitconstituting the present invention.

FIGURE 2 is a transverse cross-sectional view of a forward portion ofthe hull illustrated in FIGURE 1.

FIGURE 3 is a transverse cross-sectional view of the hull of FIGURE 1taken along the section lines 3-3 of FIGURE 1, which section is locatedrearwardly from the section of FIGURE 2.

FIGURE 4 is another transverse cross-sectional view of the hullillustrated in FIGURE 1, taken along the section lines 4-4 of FIGURE 1and at a point rearwardly of the cross-section of FIGURE 3.

FIGURE 5 is a cross-sectional view of the after portion of the hulltaken on the section lines 5-5 of FIG- URE 1 and at a point rearwardlyof the cross-section of FIGURE 4.

FIGURE 6 is a side elevation of a further embodiment of the invention.

FIGURE 7 is a transverse cross-sectional view of the hull of FIGURE 6taken on the lines 7-7 of FIGURE 6. FIGURE 8 is another transversecross-section of the hull of FIGURE 6 taken on the section lines 8-8 ofFIGURE 6 and located rearwardly of the cross-section of FIGURE 7.

FIGURE 9 is another transverse cross-section of the hull of FIGURE 6taken on the section lines 9-9 of FIGURE 6 and located rearwardly of thecross-section of FIGURE 8.

FIGURE 10 is another transverse cross-section taken on the section lines10-10 of FIGURE 6 and illustrating the cross-section at the stern of thehull of FIGURE 6.

FIGURE 11 is a plan view of the boat hull illustrated in FIGURE 1 orFIGURE 6.

FIGURE 12 is a detailed cross-sectional illustration of certain detailsof construction illustrated in FIGURES 1 through 11.

FIGURE 13 is a top or plan view diagrammatically illustrating the engineunit shown in FIGURE 1.

FIGURE 14 is an end view diagrammatically illustrating the engine unitshown in FIGURE 13.

FIGURE 15 is a detailed view of certain detachable fastenings usedbetween the boat hull and inboard engine unit.

Referring specifically now to the drawings wherein like elements aredesignated by like characters throughout, and in the first instance toFIGURE 1, the numeral 20 generally designates a power boat hullconstructed in accordance with the present invention, and provided withan engine unit generally designated at 21, the details of which will beexplained more fully in ensuing portions of this specification. The hull20 is formed around a deck 22. A keel 23 is fixed to the deck anddepends from the general plane of the deck. The keel 23 has a taperedcontour of expanding depth from the stern of the hull to the forwardportion thereof as is generally represented by the contour of the lowerline of the hull designated at 24 in FIGURE 1. The sides of the hull.are designated at 25 and 26 and extend upwardly from the deck 22 at thesides thereof. The sides of the hull may be constructed from wood, metalor plastic in any conventional fashion and contoured from the stem ofthe hull to the stern in conventional fashion as is more or lessillustrated by the contour of the hull in FIGURE 11. The deck 22 andsides 25, 26 may be reinforced in conventional fashion by ribs whichextend from the deck 22 upwardly, and by longitudinal strakes or framemembers in a manner well known to the art. The hull defined by the sides25, 26 and deck 22 may, of course, be provided with variant forms ofsuper-structure and internal accommodations. Since the super-structureand internal accommodations form no part of th present invention theyare neither shown nor described in detail herein.

In accordance with the present invention, the bottom of the hull isdefined by a flexible membrane 27 which extends from stem to stem andfrom side to side of the hull as is illustrated by the variouscross-sectional views of FIGURES 2 through 5. The flexible membrane ofFIGURES 1 through 5 is preferably made from a stretchable material suchas sheet rubber or sheet rubber substitutes so that it may be stretchedrelatively tight over the keel 23 and fixed to the sides of the hull ina manner pointed out more fully hereinafter. The membrane 27 togetherwith the deck 22 and keel 23 define air compartments beneath the planeof the deck 22, which compartments are pressurized by means of an airinlet 28 and any suitable source of air pressure as is more or lessdiagrammatically indicated by the compressor 29 in FIG- URE 1. The hullis shown in plan or top View in FIG- URE 11.

In FIGURE 6, the hull has a shape and configuration quite similar tothat of FIGURES 1 through 5 and 11, and made up of the deck 32 and sides33 and 34. In FIGURES 6 through 10, however, the bottom of the hull isdefined by a flexible but relatively non-stretchable membrane 35, whichmembrane is so shaped as to provide a bottom contour as is illustratedin FIGURES 7 through 1-0 inclusive. In FIGURES 6 through 10, no keel isnecessary. The membrane 35, together with the deck 32, define aircompartment means beneath the general plane of the deck, and thiscompartment may be pressurized by means of the air inlet 28 and sourceof air pressure designated generally at 29. The membrane 35 may be madefrom plastic or rubber with reinforcing Wire or fabric, the relativelynon-stretchable nature of the membrane 35 together with the shapethereof and the pressure in the compartment between deck 32 and membrane35 maintaining the contour of the bottom of the hull.

In all forms of the invention it is advantageous to provide some rigidsupport for the flexible membrane in the after portion of the hull. InFIGURES 1 through 5 for example, such support is provided by the sectionof the keel between the section lines 4--4 and 55. In FIGURES 6 through10, such support is provided by depressing the deck 32 from the generalplane thereof as is indicated by the dotted line 36 between sectionlines 9-9 and Iii-10. The deck may have a downwardly convex shapebetween the section lines 9-9 and 1010 as is indicated in the drawings.Thus the membrane 35 of FIGURES 6 through 10 is firmly supported alongthe longitudinal axis thereof at the rearward portion thereof. Suchsupport for the rearward or after portion of the membrane preventsbulges in the membrane under the influence of the pressure in the aircompartment. A short keel section may be used, if desired, to firmlysupport the after portion of the membrane along the longitudinal axisthereof.

If desired, a small keel-like section as indicated diagrammatically at37 may depend from the deck 32 in FIGURE 6 from a point approximatingthe section lines 7-7 to the bow so as to provide support along thelongitudinal axis of the membrane 35 at the forwardmost portion thereof.

FIGURE 12 illustrates certain details of construction which areapplicable to both embodiments in FIGURES 1 through 11. In FIGURE 12numerical designations for the deck 22, side 25, membrane 27 and inlet28 are the same as the designations used in FIGURES 1 through 6,although it should be understood that the principles set forth in regardto the details of FIGURE 12 are equally applicable to the embodiment ofFIGURES 6 through 10. In FIGURE 12 the deck 22 is shown as being sealedby a relatively thin waterproof and airtight membrane 40 which extendsover the entire under surface of. the deck 22 and is opposed to themembrane 27. The sealing. member 40' may be used when the deck 22 isformed from plywood or other equivalent material. If the deck 22 isformed from metal, plastic or other airtight and watertight materials,the sealing member 40 may be omitted. The membrane 27 is illustrated asextended upwardly a short distance alongside the sides of the hull andfixed thereto by means of screws 41 which are positioned in mountingblocks 42 and extend through the sides 25 and into longitudinalstitfeners or strakes 43 so that the ends of the membrane 27 are clampedtightly against the sides 25 and 26 of the hull. The membranes 27 and 40may be bonded to each other with the sealing membrane 40 being bonded tothe hull. If sealing member 40 is omitted, the membrane 27 may of coursebe bonded directly to the hull. The clamping action exerted by thescrews 41 and member 42 together with the bond between the membranes andthe sides is sufficient to make the construction airtight andwaterproof.

A plurality of screws 41 and members 42 may be provided at spacedintervals around the entire length of the sides of the hull. In somecases a single elongated member 42 may extend from the bow to the sternon each side of the hull with a sufficient number of screws used toensure efficient clamping action for effective sealing of thecompartment between membrane 27 and deck 22. The after portion of themembrane may be similarly secured across the stern face of the boat ormay be clamped simply to the bottom surface of the deck 22 at therearwardmost portion thereof.

The air inlet 28 for the compartment is shown fixed to a support 45,which in turn is fixed to the under portion of the deck 22 as bysuitable fastening screws. The air inlet 28 may extend within aprotective upright tube 46 which is fixed as by suitable screws to thedeck 22. The protective tube 46 should extend upwardly above the deck toa height suflicient that in the event of damage to the membrane 27,water may flow upwardly slightly within the tube 46 due to settling ofthe hull within the water without spilling out into the. interior of thehull. In oher words, the upper end of the tube 46 should be considerablyabove the water line of the hull. The tube 28 leads to a source of airpressure as has been designated generally at 29 in FIGURE 1. In someassemblies the compressor 29 may be driven from the main engines of theboat. Under other circumstances and especially in the case of smallboats at hand actuated pump may be provided to supply air through theinlet 44 to the compartment beneath the deck. The line 44 leading to theair inlet 28 may include a check valve 47 to prevent flow of air fromthe compartment to the compressor and a manually operable relief valvediagrammatically designated at 48 for reducing pressure within thecompartment from time to time in accordance with the desires of the userof the boat. The line 44 from the compressor 29 to the tube 28 in FIGURE6 may similarly be provided with a check valve 47 and relief valve 48.Thus by operating the compressor, air is delivered to the compartmentbeneath the deck, and the compartments may be pressurized to any desiredand practical degree by operation of the compressor to increase pressureor by actuating the relief valve 48 to bleed ofl pressure to theatmosphere, from time to time, to reduce pressure.

Both forms of bulls use bottoms provided with air compartment meanswhich act as a cushion over the entire bottom surface of the hull. Noreinforcing ribs between the sides and bottom are necessary as is thecase with most commercial boat constructions.

In operation the operator pressurizes the bottom compartment in anamount consonant with desired riding qualities. For example, inrelatively smooth waters the operator may use a high level of airpressure in the compartment so that the bottom is relatively rigid whileyieldable to relatively heavy forces. In rough or choppy waters, theoperator reduces the pressure in the compartment so as to allow agreater amount of flexing of the bottom when encountering Waves.

The action of the flexible bottoms when encountering waves may bedescribed as progressive flexing from the bow to the stern of the boatas the boat progresses over the wave. In other words, a wave may formsomething in the nature of a dimple in the bottom of the boat, whichdimple moves rearwardly in progressive fashion as the boat continues itsmovement over and through the wave.

Upon encountering debris such as floating planks or timber in the water,the membranes may flex inwardly against the action of the air pressurein the-compartments and absorb the shock of the blow of such foreigndebris without rupture of the membrane. During operation of the boat themembrane defining the bottom will undergo some minor degree of flexureat all times, which slight degree of flexure tends to prevent theattachment of moss or fungus to the bottom of the boat.

The form of the invention illustrated in FIGURES 1-5 allows the use ofrelatively low cost air and water tight materials such as sheet rubber.

The form of the invention illustrated in FIGURES 6 through 11 is moreshock resistant than the form illustrated in FIGURES 1 through 5, sincethe membrane is a relatively heavier material.

It should be noted that the entire bottom of the boat is supported on acontinuous mass of air from stem to stem. In FIGURES 1 through 5 thelongitudinal keel may divide this mass into two such longitudinallyextending and continuous cushions. In FIGURES 1 through 5, while thekeel is relatively rigid, the keel does not appreciably affect thecushioning action of the air mass inasmuch as each portion of themembrane on opposite sides of the keel may yield under shock of a wavewhile the keel itself presents more or less of a knife edge for cuttingthrough the wave. 7

The hull construction herein described is highly advantageous from asafety standpoint inasmuch as the flexible membrane together with theairtight and watertight deck define a double bottom construction. If forany reason the lower bottom provided by the membrane breaks, the hullwill still float due to the watertight nature of the deck opposed to theflexible membrane.

A new engine arrangement is also provided for the boat. In FIGURE 1 aseparate and detachable engine unit generally designated at 21 issupported on the stern transom of the hull. The engine unit is shown indetail in FIGURES 13 and 14. The engine unit may be comprised of agenerally box-shaped structure defined by side walls 50 and 51, a frontwall 52, a rear wall 53, and a bottom wall 54. A detachable top wall 55may be provided for the unit. The enclosure so defined by this wall isshaped and proportioned to in effect provide a continuation of the boathull from the stern aft.

The engine unit has a pair of engines diagrammatically shown at 56 and57, supported therein on any suitable frame members and at oppositesides of the unit. Engines 56 and 57 may be of the conventionalautomotive type for convenience in servicing thereof. The longitudinalaxes of the engines and the drive shafts 58 and 59 thereof are angularlydisposed and extend generally transversely of the boat. They areinclined downwardly and forwardly. Drive shaft 58 leads to aconventional automotive bevel gearing 60, whereas drive shaft 59 leadsto a similar gearing 61. Propeller shafts 62 and 63 are driven by thisbevel gearing and extend outwardly beneath the bot-tom of the unit asappears in FIGURE 1. The propeller shafts are located at right angles totheir associated drive shafts. Propellers 64 and 65 are attached to thepropeller shafts and positioned rearwardly of the rear wall 53 of theengine unit. The gear housings 60 and 61 may extend beneath the bottomwall 54 of the engine unit, the bottom wall being sealed around thehousings of the gears by means well known to the art. Whereas, the gearhousings 60 and 61 are shown as extending below the bottom of the engineunit, they may be positioned entirely within the engine unit, with thepropeller shafts then being extended through conventional sealedopenings in the bottom of the engine unit.

. The engines are located above the water line for drainage therefromoverboard. In this regard, suitable decking may be positioned beneaththe engines and above the water line so as to drain spillage from theengines overboard through suitable scu-ppers 54-b.. Decking may, forexample, be positioned on the engine support diagrammaticallyrepresented at 54-a (shown in FIGURE 14 only).

Transmissions 58-a and 59-a, which are of conventional type, areincluded between engines 56 and 57 and their drive shafts to enablechanges in direction of rotation of the propeller shafts.

It should be noted that the engines 56 and 57 are offset with relationto one another so as to avoid interference between the drive shafts 58and 59. For example, engine 56 is located slightly forwardly of engine57. Any imbalance resulting can be taken care of by suitable applicationof weights if needed.

By the transverse disposition of the engines, the engine unit can berelatively short in the longitudinal dimen- S1011.

It should be noted that the spacing of the propellers 64 and 65rearwardly of the rear wall 54 of the engine unit results in anavoidance of contact of water displaced by the propellers with thebottom wall 54 of the engine unit thereby lessening vibration.

The outer ends of the propeller shafts may be supported from straps 66(FIGURE 1) depending from the engine unit and having bearings for thepropeller shafts.

Rudder posts 67 and 68 are rotatably mounted in rearwardly extendingsupports 69 and 70 and have rudders 71 and 72 afiixed thereto andoperable by cable assemblies 73 and 74 conventional to the art. Theshowing of these rudder assemblies and the propeller shaft supportstraps has been omitted in FIGURE 14 for clarity.

It should be noted that the propeller shafts have their axes directedforwardly at a slight angle to the longitudinal axis of the hull. Thepropeller shaft axes are such that they intersect at or near the centerof effort of the hull so as to provide greater stability of operationwhen the boat is operated by a single engine.

The entire engine assembly is detachably mounted on the stern plate ortransom of the hull by shock absorb ing fastenings 75. Preferably threeor more of such fastenings are provided in symmetrically spacedrelation. Each fastening is similar in construction and is illustratedin detail in FIGURE 15. In FIGURE 15 the upright stern plate of the hullis designated at 76. Supports 77 and 78 are fixed to the stern plate 76and have spaced and opposed members 79 and 80 fixed thereto as by meansof suitable bolts or the like. The members 79 and 80 have cylindricalopenings or recesses 79a and 80a facing one another so as to receive thecylindrical ends of a-yieldable connecting element 81 therein. Theconnecting element 81 is preferably formed from rubber or some similarelastomeric material. A pin which may take the form of a bolt 82 ispassed through the central enlarged portion of the connector 81 and isthreaded into a block 83 which is fixed to the forward Wall 52 of theengine unit. Suitable lock nuts 84 may be positioned between the block83 and the opposed surface of the connector 81 so as to securely holdthe connector, engine unit and bull in the assembled relation.

, By varying the number of lock nuts 84 or by inserting spacerstherebetween, the relative spacing of the forward wall 52 of the engineunit may be varied with relation to the stern plate 76 thus allowingtilting of the engine unit about an horizontal axis for adjustment ofthe planing angle of the hull or trim thereof. Such adjustment may be.desired from time to time in order to vary the general plane of the boatwith respect to the general plane of the water.

Adjustment by remote control may also be provided by using extensiblehydraulic cylinders and rams as the supports 77 and 78, or by placing acylinder and piston between the support 83 and pin 82.

Suitable throttle controls (not shown) and rudder controls (not shown)may lead to a forward portion of the hull in a manner well known to theart. Similarly, suitable controls for the transmissions 58-a and 59-amay lead to a similar forward station in the hull.

The particular engine unit described herein minimizes vibration of thehull. The positioning of the propellers rearwardly of the rear wall ofthe engine unit minimizes the transmission of any vibration from thepropellers to the engine unit. The shock absorbing connectors 81minimize the transmission of any vibration from the engine unit to thehull.

The entire engine unit is easily removed from the hull as by looseningthe bolts 82 to allow detachment of the connecting assembly. Entireengine units may thus be easily substituted, one for the other, whileone unit is being repaired or serviced.

The use of the conventional engines, transmissions and gearing is highlyadvantageous inasmuch as units of this type are readily available on themarket and may be easily replaced.

The particular arrangement of the engine and hull assembly is alsoadvantageous from a safety standpoint. In this regard, it should benoted that if any fire exists in the engine unit, the connectors 81' mayfuse or disintegrate so as to allow separation of the engine unit fromthe hull in the event of fire. Fuel storage tanks may be carried in thehull proper and have fuel lines leading to the engine unit, in whichcase detachable connections may be provided in the fuel lines to allowfor separation of the fuel lines and detachment of the engine unit fromthe hull. The fuel tanks may also be positioned in the engine unit.

Whereas, the invention is illustrated and described herein as applied tomore or less conventional boat contours, it should be understood thatthe principles of the invention are equally applicable to variant formsof hull contours. For example, the invention may be applied to scows andboats of the type having a relatively flat prow extending transverse ofthe longitudinal axis of the boat, as is found in well known types ofamphibious craft. The flexible membranes and air compart ments hereindescribed may be applied to catamarans and to supporting pontoons foraircraft.

It should also be understood that whereas the deck depression 36 isshown as applied to the boat in FIG- URE 6, such depression may alsoadvantageously be used with the boat illustrated in FIGURE 1.

Whereas, the invention is described in terms of maintaining air underpressure in the flexible double bottom construction described herein, itshould be understood that a wide range of various pressures may be usedwith the double bottoms. For example, the pressure may be simplyatmospheric, rather than above atmospheric. This is particularly true inform of the invention illustrated in FIGURES 1 through 5, wherein theshape of the flexible membrane 27 may be maintained by stretching of themembrane 27 over the keel section 23.

Whereas, I have shown and described an operative form of the invention,it should be understood that this showing and description thereof are tobe taken in an illustrative or diagrammatic sense only. There are manymodifications to the invention which will fall within the scope andspirit thereof and which will be apparent to those skilled in the art.The scope of the invention should be limited only by the scope of thehereinafter appended claims.

I claim:

1. A boat hull construction including rigid means defining the bow,stern and sides of a hull, the bottom of said hull being comprised ofopposed waterproof and airtight members extending throughout the bottomportion thereof and spaced from one another to provide continuous aircompartment means extending continuously from the bow to the stern, andmeans for maintaining air under pressure in the compartment means sodefined.

2. A boat hull construction including means defining, a bow, stern andsides of a hull, the bottom of said hull being comprised of opposedwaterproof and airtight members extending throughout the bottom portionthereof and spaced from one another to provide continuous aircompartment means extending substantially continuously from the bow tothe stern, means for maintaining air under pressure in the compartmentmeans so defined, the innermost member being rigid, the outermost memberbeing flexible against the mass of air in said compartment means, saidflexible member being capable of progressive and continuous flexureagainst the cushioning action of said compartment means whenencountering a shock force moving from stem to stern.

3. A boat hull as set forth in claim 2 wherein said hull includes a keeldepending from said innermost member and said outermost member iscomprised of a stretchable material, the material being held undertension across said keel and fixed to the sides of the hull.

4. A boat hull as set forth in claim 2 wherein said outer member isformed from a flexible but substantially nonstretchable material and iscontoured to provide a progressively increasing spacing from said othermember, which spacing increases from the stern region to a forwardportion of said hull.

5. A boat hull including a waterproof and relatively rigid deck, meansjoined to said deck, extending upwardly therefrom and contoured toprovide the sides, bow and stern of the hull, a watertight, airtight andflexible membrane joined to the deck and the means providing the sidesand defining the bottom of said hull, said membrane being of greaterarea than said deck and defining, with said deck, fluid compartmentmeans from side to side and from stem to stern of said hull, and meansmaintaining a predetermined pressure within said compartment means.

6. The structure of claim 5 wherein said membrane is proportioned formaximum spacing from the general plane of said deck at a forward portionof said hull and for minimum spacing therefrom at the stern to define anormal planing contour.

7. The structure of claim 6 wherein rigid means are provided to supportsaid membrane along its longitudinal axis in the stern region thereofand thereby maintain the shape of the membrane.

8. The structure of claim 5 wherein the side portions of said membraneare clamped to the sides of said hull.

9. A boat hull construction including means defining a bow, stern andsides of a hull, the bottom of said hull being comprised of opposedwaterproof and airtight members extending throughout the bottom portionthereof and spaced from one another to provide continuous aircompartment means extending substantially continuously from the bow tothe stern, the outermost member being flexible, means supplying pressureto said compartment means, and means for regulating the pressure withinsaid compartment means and thereby regulating the flexibility of saidoutermost member.

10. A double-bottomed boat hull construction including rigid meansdefining the sides, bow and stern of a boat, an airtight and watertightrigid deck extending between said sides, and a flexible membrane fixedto the sides of said hull and defining the bottom of said hull, saidmembrane having a contour such that the spacing thereof from the deckincreases from the stern to a forward portion of said hull, and meansfor maintaining the space between said deck and membrane under pressure,said membrane being capable of progressive and continuous flexureagainst the cushioning action of said compartment means whenencountering a shock force moving from stem to stern.

11. The structure of claim 10 wherein said means includes an air inlettube communicating with the space between said deck and said membraneand extending through a tube fixed to said deck in upright relationthereto, the upper end of said tube extending above the water line ofsaid hull.

12. A boat hull including a waterproof and relatively rigid deck, meansjoined to said deck, extending upwardly therefrom and contoured toprovide the sides, bow and stern of the hull, a watertight, airtight andflexible membrane joined to the deck and the means providing the sidesand defining the bottom of said hull, said membrane being of greaterarea than said deck and defining, with said deck, fluid compartmentmeans from side to side and from stem to stern of said hull, said fluidcompartment means and said membrane providing a cushioning action forsaid hull when subjected to shocks encountered in moving over afloatation surface.

13. The method of operating a power boat provided with a flexiblebottom, including the steps of maintaining a mass of air under pressureagainst the flexible bottom so as to exert an outward force over thearea of said bottom, and varying the pressure of said air mass, fromtime to time, so as to thereby vary the resistance to flexure of saidbottom in accordance with desired riding and planing qualities of saidboat, the pressure being maintained at a relatively high amount duringoperation in smooth waters and maintained at a relatively low amountduring operation in rough waters.

References Cited in the file of this patent UNITED STATES PATENTS

1. A BOAT HULL CONSTRUCTION INCLUDING RIGID MEANS DEFINING THE BOW,STERN AND SIDES OF A HULL, THE BOTTOM OF SAID HULL BEING COMPRISED OFOPPOSED WATERPROOF AND AIRTIGHT MEMBERS EXTENDING THROUGHOUT THE BOTTOMPORTION THEREOF AND SPACED FROM ONE ANOTHER TO PROVIDE CONTINUOUS AIRCOMPARTMENT MEANS EXTENDING CONTINUOUSLY FROM THE BOW TO THE STERN, ANDMEANS FOR MAINTAINING AIR UNDER PRESSURE IN THE COMPARTMENT MEANS SODEFINED.